Rotary piston engine especially for fluid gears



E. STURM July 28, 1936.

ROTARY PISTON ENGINE ESPECIALLY FOR FLUID GEARS Filed April 5, 1935 I 2Sheets-Sheet l 5 e 1x i O O M N W W H H II H WLHI M 9w mm s W Q 9w %N mk k a w wx BQMH bmww wow July 28, 1936. E STURM 2,049,092

ROTARY PISTON ENGINE ESPECIALLY FOR FLUID GEARS Patented July 28, 1936'no'mar rrs'ron ENGINE asrnommr ron rwm (mans Erwin Still'm,Stuttgart-Botnang, Germany Application April 5,

In Gem This invention relates to the special construction of a rotarypiston engine with blades or vanes, in which the piston drum rotatingabout a. central journal is surrounded by a rotatable housing formingthe boundary wall of the working chamber of the engine. Such rotarypiston engines are characterized in that, whilst. they are of smalldimensions, they supply largedelivery quantities and the hydraulicfrictional losses are very small because the freely rotatable housing isrotated with the flowing fluid.

As in these engines the rotatable housing rotates in the air space, thedrawback arises in the case of high driving medium pressures, that thelateral covers of the rotary housing are pressed slightly away from theend walls of the piston drum in the middle by the high fluid pressure.this, on the one hand, increasing the normal loss due to leakage and, onthe other hand, favoring the extremely prejudicial drawing of air intothe working chamber.

This invention has for its object, to construct such a rotary pistonengine in such a manner that, even in the case of very high drivingmedium pressures, the covers cannot move away from the end walls of thepiston drum and the resulting jectionable phenomena are prevented. Thisis attained by supporting the covers of the outer housing on the hub bymeans of rings and by providing at the leakage points chambers in whichthe leakage oil collects and is, if necessary, maintained at apredetermined pressure. Thus, the leakage points of the engine aresealed by fluid so that air can no longer be drawn into the workingchamber. An airtight closure may be attained also by enabling the voil,when the engine is running. to collect and to form an oil ring under theaction of .the centrifugal force in front of the points to be 40 packed.

Further the oil flowing out of the oil chambers may, according to theinvention, be employed at t the same time for lubricating the rotatingparts of the engine.

Other features of the invention are set forth in the followingdescription of two forms of construction illustrated by way of examplein the accompanying drawings in which:--

Fig, L shows one half of a fluid gear in longitudinal section.

Fig. 2 is a cross section on line IIH of Fig. 1.

Fig. 3 is a part section on line m-m of Fig. 1.

Fig. 4 shows in longitudinal section another 55 journalling of thepiston drum in combination 1935, Serial No. 14,851

ny July 13, 1934 with a regulator for the leakage oil of modifledconstruction.

The outer housing i of a fluid gear constructed as a drivingmediumcontainer, of which only one half is shown, accommodates therotary piston engine of the fluid gear acting as a pump and mountedbetween a. partition 2 and one of the covers}.

The rotary piston engine consists of a piston drum 5 rigidhr connectedwith a driving shaft 4 and provided with a plurality of blade pistons 'lslidably mounted in radial slots 6. The piston drum 5 is journalled by ajournal 8 of the wall 2 which engages in a central bore 9 in the pistondrum. A bush i0 is provided between the piston drum and the journal. Thecounter bearing for the piston drum is in a ball bearing ll mounted inthe cover 3.

- The piston drum 5 is enclosed in a housing formed by a ring l2 and twolateral covers I3. 2 The three parts are rigidly interconnected by boltsl4. This housing is mounted freely rotatable in ball bearings l5- Itscylindrical inner surface encloses with the piston drum 5 a crescentshaped working chamber IS in which the blade 25 pistons I move. Theseare guided by annular projections II on the covers l3 against which thepistons bear by means of a hinge pin or guide bolts l8. The tightbearing of the pistons I against the inner surface of the rotary housingis ensured by similar hinge bolts or ring bolts l9v mounted in the bladepistons.

In order to prevent the'covers l3 from yielding under the high pressuresof the driving medium occurring when the engine is running and theresultant formation of a gap on the end walls of the piston drum, thehubs of the lateral covers l3 bear against annular discs mounted on theneck of the piston drum 5 and rotating therewith. These annular. discsare adjusted relative to the hubs by means of screw nuts 22.

The bearings i5 of the rotary housing are fitted in a rigid bearingframe. This frame consists of two transverse bars 23 fixed onpistonlikeguides 24. These latter are slidably mounted in bores 25 intheouterhousing I. One piston guide carries a screw spindle 21 shiftablein the cover 26 and adapted to be turned by means of a, hand lever 28,to displace the bearing frame, thereby changing the eccentricity of therotary housing relatively to the piston drum and thus altering theshape; and position of the working chamber l6.

The working chamber I6 subdivided by the blade pistons i communicateswith passages 30 29 arranged between the pistons 1 and slots in the bushl0. Each of these passages 30 and 30 forms a suction or pressure conduitof the rotary piston engine, according to the direction of delivery. Thesuction and pressure sides are separated by a partition 32 of thejournal 8 The suction and pressure passages also communicate bytransverse bores 33, 33' with bores 34, 34' in the partition 2 leadingtowards the base plate I. In these bores 34, 34' leading to the oilchamber of the gear check valves 35, 35' are fitted.

If it be supposed that the rotary housing is adjusted towards the rightaccording to Fig. 2, and the piston drum will be driven in clockwisedirection, the portion of the working chamber l6 situated above thehorizontal central plane then exerts a suction effect and the portionbelow this plane exerts a pressure effect. Driving fluid is then drawnfrom the oil chamber through the passages 34, '33, 30 and 29 into theworking chamber l6 and in the lower half of the working chamber thedriving fluid is forced through the passages 29 into the pressureconduits 36' whence it is conducted to a similarly constructed engine orto some other place of use. Flowing over of the driving fluid into theoil chamber is prevented by the pressure loaded check valve 35'.

If the rotary housing is adjusted so that it is concentric with thetakes place.

If, however, it is adjusted towards the left, the delivering directionis reversed in that the driving fluid is drawn in through the passages34, 33', 30' and 29 and is forced into the conduit 36.

The quantity and direction of delivery can be regulated by adjusting therotary housing relatively to the piston drum. As this housing is freelyrotatable, it is rotated with the driving fluid. The driving fluidtherefore flows along the housing onlyat a very slow speed, so that thefluid losses are as low as possible.

The known rotary piston engines of this type are open to the objectionthat, especially in the case of high driving fluid pressures, the coversof the rotary housing yield in outward direction, producing gaps at theend walls of the piston drum, thereby increasing the leakage losses. Astill greater objection is, that air is drawn in through these gaps andpasses into the working chamber.

The yielding of the covers is prevented by the above mentioned annulardiscs 2|. The arrangepiston drum, no delivery ment of these annulardiscs 2|, however, also enables an arrangement to be produced in whichthe natural losses due to leakage serve for efiecting an airtightclosure of the working chamber.

For this purpose annular spaces 36 and 36 are provided one on each sideof the piston drum 5 between this drum and the hubs 26 of the covers 13.These spaces intercommunicate through slots 6 and are closed laterallyby the annular discs 2|. The leakage oil fiows oil? from one of theannular spaces 36 through a passage 31 and is regulated by a controlvalve arranged in'a bore 38 in the stub axle 4. This control valveconsists of a bush 39 with a diiferential piston 4| mounted therein andforming with the bush 39 an annular space 41 in which the passage 31terminates. The differential piston is acted upon by a spring 40 so thatthe leakage oil in the spaces 36 and 36 is also maintained under thesame pressure' If the oil pressure increases, the

and 30' in the journal -8 through radial passagesdifferential piston isshifted towards the left and allows a portion of the oil to flow througha control aperture 48 which now exposes a central bore 42 in the controlpiston. The oil passes from this bore through discharge aperture 45 inthe bush 39 into a. return passage 46 leading to the oil chamber.

In this manner a predetermined oil pressure is maintained in the spaces36 and 36' and an airtight liquid seal is obtained so that no air canpass into the working chamber of the gear.

The height of the pressure can be regulated by changing-the tension ofthe spring 40 by means of an adjusting screw 49.

The pressure produced in the two spaces is utilized at the same time forcausing the blade pistons l to bear tightly against the housing wallseven when the blade pistons are not absolutely accurately fitted. It isthus possible to utilize for guiding the blade pistons annularprojections I! which can be easily provided on the covers IS.

The collecting space 36 arranged on the right hand side of the pistondrum also communicates through a passage 44 with an annular groove 54from which the journal 8, about which the piston drum rotates, receivespressure lubrication. The oil ring in the annular groove 54 serves atthe same time for preventing a sucking in of oil at: this point.

The lubricating oil flows along journal 8 and collects in a chamber 43in the end of the journal 8 and partly fi ls this chamber until it flowsoff through the central bore 42.

As the outer wall of the chamber 43 rotates, the oil is also rotated andforms, owing to the centrifugal force, an oil ring which likewiseprevents the drawing in of air between journal 8 and piston drum 5. r

Fig. 4 shows a form of construction of the rotary piston engine in whichthe piston drum 5 is mounted in conical roller bearings 50, the innerrace 5| of which bears against the annular discs 2|. The necessarymounting pressure is obtained by a screw cover 52. As the conical rollerbearings can take up considerable axial pressure, any desired pressurecan also be adjusted in the collecting chambers for the leakage oilwithout appreciably increasing the friction.

In this form of construction the chamber 36 preferably communicates bythe passage 31 directly with the chamber 43 and the pressure in the twochambers is simultaneously regulated by the check valve 53 acted upon bythe spring 46 and fitted in the bore 38. Therefore, in this instance,all the leakage points are under liquid seal. The check valve 53 openswhen the adjusted maximum pressure is exceeded and allows the leakageoil to flow off through the passage 46. This passage is so arranged thatit conducts the oil to the conical roller bearings 56 for the purpose oflubrication.

The rotary piston engine according to the invention enables theemployment of much higher driving fluid pressures than were hithertopossible in such engines and, in spite of more simple construction, itsdimensions are smaller. Moreover, the losses due to leakage are muchlower, and air is positively excluded from the working chamber. Thus,the degree of efficiency of the engine is very favorable.

I claim:-

.1. A rotary piston engine, especially for fluid gears, comprising incombination a central jour- 75 nal having inlet and outlet channels forthe driving fluid, a piston drum rotatable about said journal and havingalternating radial slots and radial channels, vanes shiftable in saidradial slots, a rotatable housing enclosing said piston drum andshittable relative to said piston drum and forming with the piston druma sickle shaped working chamber subdivided by said vanes andcommunicating by said radial channels with the inlet and outlet chambersof said central journal, covers one on each end of said housing, eachcover having an annular chamber, the chambers of both coverscommunicating by means of said radial slots, rings one on each end ofsaid piston drum and closing said chambers, a chamber at the front endof said journal and an outflow channel in said journal for the leakageoil, and channels extending from all chambers in said covers to saidoutflow channel, the leaking oil filling all said chambers during theservice and effecting by the action of centrifugal force an air-tightclosure of said working chamber.

2. A rotary piston engine as specified in claim 1, comprising incombination with the annular chambers in the covers, a piston valvearranged in the axis of rotation, a spring controlling said pistonvalve, an axial outflow channel in said piston valve controlling theoutflow of the leakage -oil from said annular chambers, and channelsconnecting the pressure space of said pis.- 110 ton valve with saidannular chambers.

3; 'A rotary piston engine as specified in claim 1, comprising incombination with the annularchambers between the covers, the rotatablehousing and the chamber on the end face of the 115 journal, a channelconnecting said annular chambers with said last mentioned chamber, andan axial outflow channel extending from snidi last mentioned chamber,and a spring controlledi valve in said outflow channel.

ERWIN STURM.

